1. Field of the Invention
The present invention relates to a game program, and in particular to a game program which allows the display position of an object displayed on a display screen to change in accordance with a change of coordinates inputted through a touch panel which is provided on the display screen.
2. Description of the Background Art
Among conventional video game machines, there exists a video game machine in which a touch panel is provided on a display screen, and the display position of a piece in a game of shogi (Japanese chess) displayed on the display screen is allowed to change in accordance with the movement of the finger on the touch panel (Japanese Patent No. 3289072). Such a video game machine allows a player to change the display position of a shogi piece displayed on the display screen as if he/she were actually moving the shogi piece with his/her finger.
In the real-world case where the movement of a real object by the finger of a person is hindered by the friction between the object and its contact surface, or by a collision with an obstacle such as a wall, the person can perceive it through the sense of touch at the fingertip.
On the other hand, in a video game machine, in the case where an object displayed on a display screen provided under a touch panel is moved by the finger of a player, even if the object is hindered from moving by a collision with an obstacle in virtual space, the player cannot perceive it through the sense of touch because the feel the player has is only the feel of sliding the finger across the touch panel. Note, however, that in this case too, the player can perceive a collision of the object with the obstacle in the virtual space through the sense of sight. For example, as shown in FIG. 11A, when the player attempts to move an object OB1 displayed at a position P0 toward the lower left of the screen, if the object OB1 stops at a position P1 shown in FIG. 11B, the player can recognize that the movement of the object OB1 is hindered by an L-shaped obstacle displayed on the screen, from the fact that the player's finger deviates from the object OB1 as shown in FIG. 11B.
Depending on the type of game, a factor (e.g., an object or physical properties) which hinders the movement of the object may not be displayed on the screen. For example, there may be a game that a player leads an object to a goal while avoiding a transparent, invisible obstacle. As another example, there may be a game that a virtual ground having an object placed thereon has different frictional forces at different points and when a player attempts to move the object over a point having a high frictional force, the object stops. As such, in some types of games, it is important to create sensations of unexpectedness that a moving object does not move according to the player's wishes, by intentionally not displaying a factor which hinders the movement of the object.
However, in the case where the factor hindering the movement of the object is not displayed on the screen, since the player's finger unexpectedly deviates from the object, the player may feel a sense of uncertainty. For example, suppose that, as shown in FIG. 12A, when the player moves an object OB1 from a position P0 toward the lower left of the screen, if the object OB1 is hindered from moving at a position P1 shown in FIG. 12B by an obstacle not being appeared on the screen or by friction, the player may consider the possibility that:                the touch panel may be partially broken down;        computer processing speed may not be fast enough to catch up with the moving speed of the finger;        a touch applied to the touch panel at the position P1 may have been weak, or the finger may have been lifted from the touch panel; or        there may be an invisible obstacle or friction.        
However, since what caused the finger to deviate from the object cannot be identified from the display screen shown in FIG. 12B, the player cannot help having a sense of uncertainty about whether the deviation was intended by the game. Under these circumstances, even if the game succeeds to create sensations of unexpectedness, the game cannot meet the player's satisfaction.
In some cases, the player may feel a sense of uncertainty, even in the case of FIG. 11B. For example, the player may mistake the L-shaped obstacle shown in FIG. 11B for just a pattern drawn on the ground, and thus the player may think that the object OB1 has stopped due to touch panel failure or misoperation.